Western Cape Premier Helen Zille is "bad" and is not fit to hold such high office, the African National Congress (ANC) leader of the opposition in the provincial legislature, Khaya Magaxa, said on Thursday.

The party said it welcomed Public Protector Busisiwe Mkhwebane's finding that Zille's now infamous tweet that not all aspects of colonialism were negative, was in violation of the Constitution and the executive ethics code.

Magaxa said the premier had "glorified the legacy of colonialism".

"She had long passed her sell-by date. She must go now, before she is further humiliated," he said at a media briefing.

"The defiant Zille's own legacy in the Western Cape is in ruins because of her continued defending the indefensible tweets, and other pronouncements that brought the province and country into disrepute."

Zille 'cowing behind freedom of speech'

Magaxa insisted Zille had no remorse.

"She tries to detract attention from the finding against her by cowing behind freedom of speech, which is not absolute. In fact, Zille keeps on digging deeper the pit she made for herself.

"By deflecting attention onto the Public Protector, the Democratic Alliance (DA) and Zille clearly are illiberally not submitting themselves to our Constitution and the rule of law. They are not above the law, beyond reproach or untouchable. The Public Protector's mandate is a legal duty to investigate ethics complaints."

Last year, Magaxa lodged a complaint with the Public Protector, saying that Zille's tweet was a breach of the Executive Ethics Act and Code.

He said it was "astounding that the DA cheers when the very same act is used against its opposition but comes out kicking and screaming when the DA is at the receiving end".

"It is also raw irony that the DA uses the same executive ethics act against other people, and now they question it."

Zille 'must go now'

Magaxa reiterated that Zille "must go now".

"She keeps embarrassing the people of this province and hurts more people across our nation now than with her initial tweets a year ago.

"She is a rebellious person that continues to drag down the name, image and brand of the province. The ANC calls on the Western Cape legislature to speed up the process to hold Zille to account, to censure her."

On Monday, Zille's spokesperson Michael Mpofu said the premier was likely to take the report on judicial review.

"The premier has already advised the Public Protector that, in her view, such a finding would be unlawful and irrational," he said at the time.

As part of her recommendation on remedial action, Mkhwebane has instructed the speaker of the Western Cape legislature to take appropriate action and hold Zille accountable for her conduct.